- remove reduce_invertible. It is subsumed by reduce_uncstr(2)
- introduce a simplifier for reduce_unconstrained. It uses reference counting to deal with inefficiency bug of legacy reduce_uncstr. It decomposes theory plugins into expr_inverter.
reduce_invertible is a tactic used in most built-in scenarios. It is useful for removing subterms that can be eliminated using "cheap" quantifier elimination. Specifically variables that occur only once can be removed in many cases by computing an expression that represents the effect computing a value for the eliminated occurrence.
The theory plugins for variable elimination are very partial and should be augmented by extensions, esp. for the case of bit-vectors where the invertibility conditions are thoroughly documented by Niemetz and Preiner.
the solve_eqs_tactic is to be replaced by a re-implementation that uses solve_eqs in the simplifiers directory.
The re-implementation should address efficiency issues with the previous code.
At this point it punts on low level proofs. The plan is to use coarser
dependency tracking instead of low level proofs for pre-processing. Dependencies can be converted into a proof hint representation that can be checked using a stronger checker.
* Memory leak in .NET user-propagator
The user-propagator object has to be manually disposed (IDisposable), otherwise it stays in memory forever, as it cannot be garbage collected automatically
* Throw an exception if variable passed to decide is already assigned instead of running in an assertion violation
* Added limit to "visit" to allow detecting multiple visits
* Putting visit in a separate class
(Reason: We will probably need two of them in the sat::solver)
* Bugfix
* Memory leak in .NET user-propagator
The user-propagator object has to be manually disposed (IDisposable), otherwise it stays in memory forever, as it cannot be garbage collected automatically
* Throw an exception if variable passed to decide is already assigned instead of running in an assertion violation
* Added 64-bit "1" counting
simplifiers layer is a common substrate for global non-incremental and incremental processing.
The first two layers are new, but others are to be ported form tactics.
- bv::slice - rewrites equations to cut-dice-slice bit-vector extractions until they align. It creates opportunities for rewriting portions of bit-vectors to common sub-expressions, including values.
- euf::completion - generalizes the KB simplifcation from asserted formulas to use the E-graph to establish a global and order-independent canonization.
The interface dependent_expr_simplifier is amenable to forming tactics. Plugins for asserted-formulas is also possible but not yet realized.
- ensure mk_extract performs simplification to distribute over extract and removing extract if the range is the entire bit-vector
- ensure bool_rewriter simplifeis disjunctions when applicable.
Removing ternary clause optimization from sat_solver simplifies special case handling of ternary clauses throughout the sat solver and dependent solvers (pb_solver). Benchmarking on QF_BV suggests the ternary clause optimization does not have any effect. While removing ternary clause optimization two bugs in unit propagation were also uncovered: it missed propagations when the only a single undef literal remained in the non-watched literals and it did not update blocked literals in cases where it could in the watch list. These performance bugs were for general clauses, ternary clause propagation did not miss propagations (and don't use blocked literals), but fixing these issues for general clauses appear to have made ternary clause optimization irrelevant based on what was measured.
* Allow reseting the stream of smt2::scanner
* Put the parser of parse_smt2_commands in the cmd_context
* Move parser streams to cmd_context
* Move parser fields from cmd_context to api::context
* Move forward declarations from cmd_context.h to api_context.h
* Change parse_smt2_commands_with_parser to use *& instead of **
* Add tests for Z3_eval_smtlib2_string
* Don't reuse the streams in Z3_eval_smtlib2_string
* Fix indentation
* Add back unnecessary deleted line
Co-authored-by: Nuno Lopes <nuno.lopes@tecnico.ulisboa.pt>
gc-ing definitions leads to unsoundness when they are not replayed.
Instead of attempting to replay definitions theory internalization is irredundant by default.
This is also the old solver behavior where TH_LEMMA is essentially never used, but is valid for top-level theory lemmas.
So far the format is
(forall ((x Int)) body) (not (body[t/x]))
The alternative could be the clause
(not (forall ((x Int)) body)) body[t/x]
they just better be consistent between engines
